A day after SpaceX’s final flight of Starhopper— a stubby prototype of an enormous planned launch system, called Starship— company founder Elon Musk dropped a clue about his super-size plans for the future.
Musk tweeted on Wednesday that he’ll present SpaceX’s latest thinking about the Starship system on September 28. The date marks the 11th anniversary of the company reaching orbit for the first time with its Falcon 1 rocket.
Until then, most of what we know about Starship comes from Musk’s latest presentation from September 2018. At that time, the vehicle was still called the “ Big Falcon Rocket” and was supposed to be made out of carbon-fiber composites. SpaceX is now using stainless steel but appears to be keeping similar dimensions, based on several renderings posted by Musk (including one of a Starship spaceship on the moon’s surface).
Those dimensions suggest the first operational version of Starship would be a vehicle about 30 feet (9 meters) wide and 387 feet (118 meters) tall. Yet Musk is already dreaming up an even bigger version of the system.
He revealed part of his grand plan on Wednesday when a Twitter user asked about a 39-foot-wide (12 meters) version of Starship. Musk replied that a “next-gen” version of Starship would probably be double that diameter: a width of 18 meters, or nearly 60 feet.
That’s wider than an NBA basketball court. The footprint of such a rocket would also be 30% greater than the square footage of an average US home.
The following graphic shows about how big the first Starship system would be compared to its prototypes, such as Starhopper and Starship Mark 1. The Apollo-era Saturn V rocket and NASA’s upcoming Space Launch System moon rocket are also included for scale.
However, performing some basic math helps reveal the scale of what Musk is proposing to do with SpaceX in the far-flung future.
A ‘next gen’ Starship may have 8 times the volume of the first operational Starship
Simplifying the dimensions of the first-generation Starship into a cylinder (and ignoring its aerodynamic nosecone) gives a finished volume of about 7.5 million liters. The same calculation on the next-generation Starship — assuming its height also doubles, to about 775 feet (236 meters) — gives an approximate volume of 60 million liters.
So in effect, doubling the width and height leads to a launch vehicle about eight times as voluminous. Even if the next-generation Starship was just as tall as the first one, its increased girth would make it about four times times bigger.
Boosting Starship’ volume so much says little about how much payload or people a next-generation Starship could haul into orbit, or how deep into space such a gigantic spacecraft could go. But it’s hard not to imagine the answers are “more, bigger, faster, and farther” since it could carry that much more fuel and make room for many more Raptor rocket engines.
Certainly, a nosecone with basketball-court-width diameter is larger than that of any currently planned rocket’s.
Such a size could accommodate space telescopes that astronomers may only dream of right now. For example, NASA’s upcoming James Webb Space Telescope will fold up into a 15-foot-wide (4.57 meter) fairing of an Ariane 5 rocket around 2021. If a next-gen Starship is ever realized, it might fit six or more of the $10-billion space observatories inside its fairing.
However, Musk envisions building a city on Mars that will be self-sustaining by the 2050s (and eventually has pizza joints). If he hopes to see that mission accomplished before his time on Earth is done, though, SpaceX may need the biggest rocket its leader can dream up.
